Related art of the present disclosure is described in Japanese Unexamined Patent Application Publication No. 2008-154267 (PTL 1). FIG. 1 is a perspective view of a communication unit described in PTL 1. A coupling electrode 108 and a folded stub 103 are formed, respectively, on the upper and lower surfaces of a spacer 109 made of an insulator. The coupling electrode 108 is connected to a central portion of the stub 103 via a through hole (plated through hole) 110 inside the spacer 109. A signal line pattern led out of a transmission/reception circuit module 105 and a conductive pattern 112 connected to a ground conductor 102 via a through hole 106 inside a printed board 101 are formed on the printed board 101. When the spacer 109 is mounted on the printed board 101, ends of the stub 103 are connected to the signal line pattern 111 and the conductive pattern 112.
FIG. 2 is an equivalent circuit diagram of a communication device including two communication units shown in FIG. 1. Inductors L110 each arranged between the transmission/reception circuit module 105 and the coupling electrode 108 are inductors each formed by the through hole 110 shown in FIG. 1. Inductors L103, each of which are connected in shunt between a line to which the inductor L110 is connected and the ground, are inductors each generated by the stub 103 shown in FIG. 1.